$highhlight-color: #f90;
$basic-border: 1px solid #000;
$nav-color: #f90;
#app {
  background-color: $highhlight-color;
  border: $basic-border
}
nav {
  $width: 100px;
  color: $nav-color;
  width: $width;
  background-color: #000;
}
#content {
  article {
    h1 { color: #1dc08a }
    p {  font-style: italic; }
    a {
      color: blue;
      &:hover { color: red }
    }
  }
  aside { background-color: #f90 }
}